I was riding a BMW R1100RT which got to be a little too heavy and too tall especially when riding 2-up. Bought the 2010 RT and we have been very happy with it. My wife loves it and I consider it to be the best touring machine I've ever owned. I kept the BMW when I bought the RT but found I wasn't riding it much and, when a friend wanted to buy it, I sold it. But, yes, I missed riding 2 wheels.
At 75, I didn't think I was too old to ride a 2-wheeler but I got to thinking that if I didn't ever ride one I might get to be too old and that bothered me. I had a chance to buy a very low mileage, well maintained 2003 BMW F650CS at a decent price so I bought it. The CS is a light, short, very maneuverable, single. It is not a touring bike by any stretch of the imagination but, for short rides to breakfast or lunch with a small group or just a little 50 - 100 mile ride to clear my head, it is a blast to ride. I didn't really realize how much I really missed two wheels until I got back on two wheels. Now, when I ride solo, I almost always ride the BMW.
I'm really glad we got the Spyder. I doubt that my wife would even be riding with me if not for it. She was tired of being dropped and worried that the next time it happened might be in traffic where something serious could happen. We both love touring on the RT or just taking short rides around home 2-up. At the same time, I'm glad I got the BMW and I'm really enjoying being on 2 wheels again when I'm riding solo. So, my advice, for what it's worth: I think you'll love the Spyder but, if you are worried that you may miss the 2 wheeler, try to find a way to keep it or maybe buy a cheaper one so you can still ride 2 wheels also. Two wheels and three wheels are distinctly different pleasures. I don't want to give up either one.
Cotton